/Engine/Source/Runtime/ApplicationCore/Public/GenericPlatform/GenericPlatformApplicationMisc.h
If we know or can approximate the pixel density of the screen we will convert the incoming inches to pixels on the device. If the accuracy is unknown OutPixels will be set to 0.
template<typename T, typename T2, typename [TEnableIf](API\Runtime\Core\Templates\TEnableIf)< [TIsFloatingPoint](API\Runtime\Core\Templates\TIsFloatingPoint)< T >::Value &&[TIsFloatingPoint](API\Runtime\Core\Templates\TIsFloatingPoint)< T2 >::Value, int >::type> static EScreenPhysicalAccuracy ConvertInchesToPixels ( T Inches, T2 & OutPixels )